In todays complex society individuals carry numerous important documents such as credit cards, drivers licenses, key cards and other identification means on their person in card carrying cases or wallets. These items are removed from their cases repeatedly and in most instances termporarily given to other persons when the owner is making a purchase, cashing a check or engaged in a variety of different functions. Due to the relatively inconspicuous nature of the documents, they can be forgotten and left on a counter, with another person, or in a lock. Furthermore, credit cards are extremely valuable property much sought after in the criminal world and thus subject to being stolen when left unattended. Although inconspicuous, they are immensely important to the owner and difficult to replace. Therefore, it is desirable to have a means to alert a person when he has removed a document from its carrying case and not returned it after a predetermine period of time.
Attempts have been made to solve the foregoing and similar problems but they failed to meet all of the needs. For instance, U.S. Pat. No. 3,648,832 discloses a card carrying case which remains in an open condition when a card is removed. This renders a case difficult to return to a tight pocket without the card but does nothing to prevent its placement in a purse or loose pocket or to prevent it from being left on a counter.
U.S. Pat. No. 3,701,987 discloses a system which provides an indication when a card is not returned to its proper place in a file. This system requires that each card or document have a conductive strip thereon. Since placement of a conductive strip on all the documents one would carry is impractical and in some cases impossible, this system can not be readily adapted to a card carrying case. Furthermore, it would present an alarm concition as long as a document is removed and thus it would be an annoyance while a transaction is taking place and possibly a user would become accustomed to the alarm and thus defeat any monitoring functions it might serve.